Silence Your Gear!!! Power Cord Polarity...

[Phil H]

Just remember: Black to brass will save your ass

No more than 500ua leakage current..... Oh you were talking about Stereo gear..... Sorry for being a smart ass. :uzi: :uzi:

I ought to put a grounded plug set up on one of the recievers and bring home a Safety Analyzer and see what shows up.

Or just set your Multimeter to read ua and go from chassis to ground. Any more than 800ua and I would not get damp and grab the monster. You just might discover how well the human body conducts.....

Sorry for going off topic but safety is one of my jobs and I lost a friend years ago on 80ua. It was at 100kvp. Just remember that ohms law.

Class A GFCI's (the GFI's found in homes, swimming pools, etc) are designed to trip when 4mA to 6mA goes to ground. Worrying about 800 μA at 120V is a bit conservative.

 

[KeninDC]

Once again, great advice from Rob Merrylander. I messed with my Yamaha CR 1020 last night and was still getting a "hum/buzz" from both speakers that was not present when I had the Yamaha in my upstairs set up. Turned out, unplugging the TV from the same socket eliminated the buzz.

I reckon I need to properly ground the socket this weekend which most likely caused the TV interference according to an engineer I work with.

 

[Ghog]

Merrylander, I had a "problem" with the right power meter on my CR-2040 when I first got it. It is supposed to switch to "signal strength" immediately when you touch the tuning knob, but mine switched any time I got my hand near it. The "problem" eventually went away. I unplugged it yesterday to do a little work on it, and when I turned it on on my bench, the "problem" was back :headscrat . A little while later I noticed it was back to operating correctly. Then I dawned on me what was happening. I pulled the plug and flipped it, and the "problem" came back. That's when I remembered this thread from a few days ago. Reminds me of that old saying about blind squirrels.......

 

[Ausjoe]

I checked polarity on a piece of gear today. Do this as a matter of course on all two prong gear. When I did a search to see if anyone had passed this info on Echowars had so instead of a new thread revived this one. There are a lot of new members and the first post describing what you are trying to accomplish is still useful if you don't already know. Only thing I'd add is I use red paint to mark the hot but you can mark common if you wish. Might make a corresponding mark on the outlet if you are forgetful!

 

[jstang]

So far all of the Yammies I have serviced have the side of the line cord with a rib, white tracer, or writing, connected to the side that has the 2.2 megohn resistor run to the chassis. Put that prong in the wide blade opening of the receptacle and you are good to go. When I have had the occasion to replace a line cord I follow their practice. This happens mainly with the multi-voltage models and the standard seemss to be brown wire = hot, blue wire = ground.

A very good reason for following this rule is that not all test equipment has isolated ground and you may rest assured that ALL of my test equipment has been verified as having the chassis at ground potential. Do not want to let out the magic smoke.

Rob

Marantz receivers from the 70s have the 2.2mOhm resistor too. The US made Marantz separates that I own do not the resistor. There does not seem to be any good indication on the receivers that I have for which prong is connected to ground via the resistor, so I measured it.

I have forgotten what this resistor is there for... Safety precaution of some type I seem to remember, but it raises chassis noise.

I have made a fair amount of power mods to my main system ( US made Marantz separates)....Two dedicated 120V 20a line via 10 Gauge wire from the two different hots and a dedicated 240V 20a line via 10guage for the Amps.

This includes an Exact Power regenerator, a Monster power and a home made RFI/EMI unit for the 240V.

I checked for voltage potential from every device chassis to every other.... I found 60Vac on one device.... it turned out to be a loose ground connection inside the chassis ( not my home made ) that device does have ground prong on the cord, but the chassis side was loose.....

I am glad I found that with a voltmeter and not with my tongue.....

The system is the dead quiet even with the Volume at Max & nothing playing.

jk

 

[cdfac]

so if i'm getting a ground loop immediately after adding a newer 3-prong preamp into an otherwise unpolarized vintage setup, then i should first try experimenting with reversing the plugs on the two amps? it seems like one of those units must be the problem because i just ran a new dedicated line and i know that ground is good. the hum wasn't TOO bad to begin with, and decreased about by about 75% when i threw in a floating cheater plug for the preamp, but i can still hear it since i know it's there.